1. Field of the Invention
The subject invention relates to user interfaces for video editors. More particularly, the invention relates to the use of blocks in a workspace window that depict various video elements and which attract or repel other blocks as a function of proximity to each other in order to reduce user errors and to improve user efficiency.
2. Description of the Prior Art
A video consists of electronically stored images called frames that are played back on a video display terminal such as a CRT. Videos may be in either an analog or digital format. However, the digital computer has proven to be very useful in editing video. Thus, many analog videos are converted to digital for editing. The present invention relates to the editing of digital videos. A digital video is a sequence of image frames that are stored in the memory of a digital computer and replayed in frame sequence at a high frame rate, called video rate, to provide full motion images. Because computers have limited memory and because videos consume large amounts of memory, most videos are stored in a compressed format. The compression format standard currently in wide use is called Motion Picture Experts Group ("MPEG") which is described in detail in the following documents which are hereby incorporated by reference: (1) a document entitled Generic Coding of Moving Pictures and Associated Audio Information; Video, ISO/IEC 13818-2; (2) a document entitled Coding of Moving Pictures and Associated Audio for Digital Storage Media at up to about 1.5 MBit/sec (Part 3 Audio) 3-11171 rev 1 (1995); and (3) a document entitled Generic Coding of Moving Pictures and Associated Audio Information ISO/IEC 13818-3. All above-referenced MPEG standard documents may be obtained from ISO/IEC Case Postale 56, CH 1211, Geneva 20, Switzerland.
Video elements consist of digital files containing sound, video clips, still pictures, overlays and transitions. Video editors are in general used to arrange and modify these elements. In the context of the present invention, video clips and sound are illustrated as-blocks on the user interface. The user may rearrange the blocks, add overlays and transitions. In this way, the user forms a long track of frames which constitute the edited video. Because the user is constantly manipulating blocks on a workspace window, it is desirable to have the blocks behave in a most convenient and intuitive manner.